I’ve trapped all the groundhogs on my 20 acres. Used to be many, many burrows along the fence lines. Generally, I’m told, groundhogs make one burrow in the woods, and a second in the field to allow safe escape from predators. Any time we found one, we “smoked” it to find the other openings (lit newspaper tossed in, spray with water, make smoke). Tried a few ways to discourage, then we got discouraged. Started live trapping. Neighbor suggested never cleaning the cage as one groundhog’s poop would attract another. Worked for us. Sometimes we used lettuce. Be aware that other critters will live in the holes, too. Over the years I caught 'coons, cats, possums, skunks, and squirrels. I release everything in a state park far, far from my house --except the cats I have neutered/spayed and release back on the farm. BUT I do not release groundhogs. They go to groundhog heaven as I worry that any release will result in a hole that some horse will step in --maybe not mine, but there are lots of horses in my area.
As one poster pointed out, a good dog is an asset. We had a JRT who would go down and drag the groundhogs out of their dens and dispatch them on the way to the surface. Quick and clean. Still miss that dog.
As “cute” as the critters are, a horse stepping into a groundhog hole is a horrible thought --especially at speed. We use our fence lines for conditioning. Our method of dispatch is quick.
Foxglove